Considerable efforts in the prior art have been devoted to the electrodeposition of lithium to form lithium sheets, strips or the like. One of the major requirements in the electrodeposition of lithium is to obtain a deposition of nondendritic, adherent, flat lithium deposits. Many electrolytes, particularly many known organic electrolytes, tend to produce only dendritic or mossy lithium on plating, sometimes accompanied by gas evolution. Deposits of these types tend to spall off the lithium electrode substrate. U.S. Pat. No. 3,580,828 discloses that the electrodeposition of lithium from an electrolyte comprising a lithium salt in a nonaqueous organic liquid solvent, such as propylene carbonate, will produce a dense, coherent deposit of lithium on a substrate if carried out under precise concentration and current density limits.
It is an object of the present invention to provide an electrolyte comprising lithium fluoroborate dissolved in a mixture of methylene chloride and sulfolane and/or the alkyl-substituted derivatives thereof.
It is another object of the present invention to provide a process for electrodeposition of a dense, cohesive deposit of lithium from a nonaqueous electrolyte comprising lithium fluoroborate dissolved in a mixture of methylene chloride and sulfolane and/or the alkyl-substituted derivatives thereof.